Conventionally, there is known a conveying robot that conveys a substrate, such as a wafer, into or out of a processing apparatus in a semiconductor manufacturing process in a space formed in a local cleaning apparatus called an EFEM (Equipment Front End Module).
A conveying robot that conveys a substrate generally includes an arm provided with a holding unit, which holds a substrate, at the tip thereof and conveys a substrate by operating the arm and the holding unit in a horizontal direction while holding the substrate, for example, by placing it on the upper surface of the holding unit.
Examples of such a conveying robot include one that includes a plurality of holding units and conveys a plurality of substrates in parallel by individually operating the holding units on the planes parallel to each other (for example, see Japanese Patent Laid-open Publication 2007-005582).
A semiconductor manufacturing process includes processing of heating a substrate, such as baking processing. Therefore, the conveying robot that includes a plurality of holding units in some cases needs to perform an operation of conveying a room-temperature substrate before the processing by another holding unit in parallel with an operation of conveying a high-temperature substrate after the processing by a holding unit.
However, in the conventional conveying robot including a plurality of holding units, another holding unit is adversely affected in some cases by the radiation heat radiated from the holding unit during conveying of the high-temperature substrate or the radiation heat radiated from a heated substrate during conveying.
For example, when a holding unit conveying a high-temperature substrate and a holding unit conveying a room-temperature substrate are brought into a positional relationship in which they are vertically close to each other, the holding unit conveying the room-temperature substrate may be adversely affected by the radiation heat radiated from the holding unit conveying the high-temperature substrate or the radiation heat radiated from the heated substrate during conveying.